A conventional cellular radiotelephone has an antenna for transmitting and receiving radio signals to and from a cellular base station. The antenna is typically a half-wave dipole antenna mounted on the exterior of the cellular radiotelephone. In the 800-900 Mhz frequency range, the length of a half-wave dipole is on the order of 80 mm. As the size of cellular radiotelephones has decreased, the antenna has become relatively large with respect to the body of the cellular radiotelephone. The relative size of a conventional half-wave dipole antenna may make a small radiotelephone inconvenient to place in a shirt pocket. The relative size of the antenna may also make the radiotelephone cumbersome to use, and may also result in shielding of the antenna during use by the user's head.
An antenna on a cellular radiotelephone is disclosed in U.S. Pat. No. 4,868,576 to Johnson entitled "Extendable Antenna for Portable Cellular Telephones with Ground Radiator." In this patent, the cellular radiotelephone includes an extendable antenna system. This antenna system may, however, be difficult to implement in a small hand-held radiotelephone because of the internal space required to store the antenna when retracted. Furthermore, this type of antenna may be shielded by the user's head during use.
Another approach has been to provide an antenna on the side of the cellular radiotelephone as in the Ericsson DH-198 radiotelephone, for example. This antenna is located on a side of the radiotelephone and rotates 360 degrees in a plane perpendicular to the face of the telephone. Accordingly, the antenna may be rotated to a downward position for storage, and to an upward position for use. This antenna may, however, suffer from reduced gain when the antenna is in a downward position, and it may not be mechanically durable.
Notwithstanding the above-mentioned antennas, there continues to exist a need in the art for a durable antenna for a cellular radiotelephone which provides convenient storage and use positions as well as consistently high gain.